The goal of this project is to explore the therapeutic potential and biological effects of autologous plasma perfused over protein A in patients with breast cancer. Patients with recurrent measurable breast cancer and good performance status are treated with previously stored autologous plasma perfused over protein A immobilized on charcoal collodion. The dose of protein A and the quantities of plasma perfused are escalated in a stepwise fashion depending on the patient's tolerance. The patients are closely observed for evidence of objective tumor regression, inflammatory changes around the lesions, toxicity, and immune modulation. Seven patients have undergone 11 courses of therapy to date. Some patients have experienced tumor pain following plasma therapy but there have been no objective tumor regressions. Animal studies performed by direct injections of protein A in three animal tumor models have not shown any antitumor effects. In vitro studies have been performed to explore the antiproliferative and anticlonogenic effects of protein A in the presence of human serum (complement) and/or a monoclonal antibody recognizing an antigen expressed by the cultured tumor cells. Although protein A may exert some complement-dependent effect to reduce colony growth in the clonogenic assay system, there has been no synergistic cytotoxicity with the monoclonal antibody in these preliminary in vitro experiments.